One and Two-STAGE BINOMIAL OPTION PRICING MODEL - Method...
Transcript of One and Two-STAGE BINOMIAL OPTION PRICING MODEL - Method...
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
1
LECTURE 9
One and Two-STAGE BINOMIAL OPTION PRICING MODEL - Method 2
INPUT OUTPUT
Example I - Single Stage (Call Option) PERIOD 0 PERIOD 1
S = 4500$
u = 110x Su= 4950 Cu= 950
d = 090x
X = 4000$ S = 4500 690
i = 500
Freq= 1 Sd = 4050 Cd= 050
Stages= 1
p = 075
1-p= 025
C= 690
Example II (Call option w no Dividends) PERIOD 0 PERIOD 1 PERIOD 2
Su^2= 5445 Cu^2= 1445
S = 4500$
u = 110x Su= 4950 C1= 1140
d = 090x
X = 4000$ S = 4500 892 4455 Cud= 455
i = 500
Freq= 1 Sd = 4050 C2= 325
Stages= 2
p = 075 Sd^2= 3645 Cd^2= 000
1-p= 025
C= 892
Example III (Put Option w no Dividends) PERIOD 0 PERIOD 1 PERIOD 2
Su^2= 7502 Pu^2= 000
S = 6200$
u = 110x Su= 6820 064
d = 095x
X = 7000$ S = 6200 125 6479 Pud= 521
i = 800
Freq= 1 Sd = 5890 591
Stages= 2
p = 087 Sd^2= 5596 Pd^2= 1405
1-p= 013
P= 125
Example IV (Call Option w Dividends) PERIOD 0 PERIOD 1 PERIOD 1(x-div) PERIOD 2
Su^2= 3729 Cu^2= 1229
x-dividend
S = 3000$ Su= 3450 3243 862
u = 115x
d = 090x S = 3000 584 2919 Cud= 419
X = 2500$ 2919
i = 500 Sd = 2700 2538 239
Div (δ)= 600
Sd^2= 2284 Cd^2= 000
Freq= 1 p = 060
Stages= 2 1-p= 040
C= 584
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
2
BLACK-SHOLES OPTION PRICING MODEL
The BlackndashScholes model is a mathematical description of financial markets and
derivative investment instruments The model develops partial differential equations
whose solution the BlackndashScholes formula is widely used in the pricing of European-
style options
Black-Scholes Model - Definition
A mathematical formula designed to price an option as a function of certain variables-
generally stock price striking price volatility time to expiration dividends to be paid
and the current risk-free interest rate
Black-Scholes Model - Introduction
The Black-Scholes model is a tool for equity options pricing Prior to the development of
the Black-Scholes Model there was no standard options pricing method and nobody can
put a fair price to charge for options The Black-Scholes Model turned that guessing
game into a mathematical science which helped develop the options market into the
lucrative industry it is today Options traders compare the prevailing option price in the
exchange against the theoretical value derived by the Black-Scholes Model in order to
determine if a particular option contract is over or under valued hence assisting them in
their options trading decision The Black-Scholes Model was originally created for the
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
3
pricing and hedging of European Call and Put options as the American Options market
the CBOE started only 1 month before the creation of the Black-Scholes Model The
difference in the pricing of European options and American options is that options
pricing of European options do not take into consideration the possibility of early
exercising American options therefore command a higher price than European options
due to the flexibility to exercise the option at anytime The classic Black-Scholes Model
does not take this extra value into consideration in its calculations
Black-Scholes Model Assumptions
There are several assumptions underlying the Black-Scholes model of calculating options
pricing The most significant is that volatility a measure of how much a stock can be
expected to move in the near-term is a constant over time The Black-Scholes model also
assumes stocks move in a manner referred to as a random walk at any given moment
they are as likely to move up as they are to move down These assumptions are combined
with the principle that options pricing should provide no immediate gain to either seller
or buyer
The exact 6 assumptions of the Black-Scholes Model are
1 Stock pays no dividends
2 Option can only be exercised upon expiration
3 Market direction cannot be predicted hence Random Walk
4 No commissions are charged in the transaction
5 Interest rates remain constant
6 Stock returns are normally distributed thus volatility is constant over time
As you can see the validity of many of these assumptions used by the Black-Scholes
Model is questionable or invalid resulting in theoretical values which are not always
accurate Hence theoretical values derived from the Black-Scholes Model are only good
as a guide for relative comparison and is not an exact indication to the over or under
priced nature of a stock option
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
4
Model assumptions
The BlackndashScholes model of the market for a particular equity makes the following
explicit assumptions
It is possible to borrow and lend cash at a known constant risk-free interest rate
This restriction has been removed in later extensions of the model
The price follows a Geometric Brownian motion with constant drift and volatility
It follows from this that the return is a Log-normal distribution This often implies
the validity of the efficient-market hypothesis
There are no transaction costs or taxes
The stock does not pay a dividend (see below for extensions to handle dividend
payments)
All securities are perfectly divisible (ie it is possible to buy any fraction of a
share)
There are no restrictions on short selling
There is no arbitrage opportunity
Options use the European exercise terms which dictate that options may only be
exercised on the day of expiration
From these conditions in the market for an equity (and for an option on the equity) the
authors show that it is possible to create a hedged position consisting of a long position
in the stock and a short position in [calls on the same stock] whose value will not depend
on the price of the stock[3]
Several of these assumptions of the original model have been removed in subsequent
extensions of the model Modern versions account for changing interest rates (Merton
1976) transaction costs and taxes (Ingerson 1976) and dividend payout (Merton 1973)
The Black Scholes formula calculates the price of European put and call options It can
be obtained by solving the BlackndashScholes partial differential equation
The value of a call option in terms of the BlackndashScholes parameters is
C (St) = SN (d1) ndash Xe ndashr(T-t)
N(d2)
d1 = [ ln (SoX) + (r + σ2 2) (T ndash t) ] [ σ SQR of (T ndash t) ]
d2 = d1 ndash σ SQRT of (T ndash t)
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
5
The price of a put option is
P (S t) = Xe ndashr(T-t) ndash S+(SN(d1) ndash Xe ndashr(T-t) N(d2)) = Xe ndashr(T-t) ndash S+C (St)
For both as above
N(bull) is the cumulative distribution function of the standard normal distribution
T - t is the time to maturity
S is the spot price of the underlying asset
X is the strike price
r is the risk free rate (annual rate expressed in terms of continuous compounding)
σ is the volatility in the log-returns of the underlying
Interpretation
N(d1) and N(d2) are the probabilities of the option expiring in-the-money under the
equivalent exponential martingale probability measure (numeacuteraire = stock) and the
equivalent martingale probability measure (numeacuteraire = risk free asset) respectively The
equivalent martingale probability measure is also called the risk-neutral probability
measure Note that both of these are probabilities in a measure theoretic sense and
neither of these is the true probability of expiring in-the-money under the real probability
measure In order to calculate the probability under the real (physical) probability
measure additional information is require
dmdashthe drift term in the physical measure or equivalently the market price of risk
Example
Suppose you want to value a call option under the following circumstances
Stock Price S0 = 100
Exercise Price X=95
Interest Rate r= 10
Dividend Yield δ = 0
Time to expiration T = 25 (one-quarter year)
Standard Deviation σ = 50
First calculate
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
6
d1 = [ln (10095) + (10-0 + 522)25] [ 5 SQRT of 25] = 43
d2 = 43 - 5 SQRT of 25 = 18
Next find N (d1) and d N(d2) The normal distribution function is tabulated and may be
found in many statistics books A table of N (d) is provided as Table 162 in the book
page 521 The normal distribution function N(d) is also provided in any spreadsheet
program In Excel the function name is NORMSDIST so using EXCEL (using
interpolation for 43) we find that
N(43) = 6664
N(18) = 5714
Finally remember that with dividends (δ) = o
S0 e ndash δT
= S0
Thus the value of the call option is
C = 100 x 6664 ndash 95e -10x025
x 5714
=6664 ndash 5294 = $1370
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
7
BLACK-SCHOLES OPTION VALUATION METHOD BS - CALL OPTION
A B C D E F G Compound at e
5
6 INPUT OUTPUT Face Value 100$
7 Interest 10
8 Standard Deviation (σ) = 05 d1 = 0430 Years 109 Expiration (in years) (T) = 025 d2 = 0180
10 Risk-Free Rate (Annual) (i) = 01 N(d1) = 0666 Description Compound FV
11 Stock Price (S ) = 100 N(d2) = 0571 Annual 1 25937425 12 Exercise Price (X) = 95 Semi 2 26532977
13 Dividend Yield (annual) (δ) = 0 C = 136953 Quarterly 4 26850638 Monthly 12 27070415
Daily 365 27179096
LONG CALCULATION (Break Down Approach) Hourly 8760 27182663
D1 = Ln ( S X ) ( i-δ+σ^2 2 ) σradict By Minute 525600 27182816 D1 = 0051293294 005625 025 By Second 31536000 27182819
Infinite e 27182818
D1 = 043017
N (d1) = 066647
PV calculation using e
D2= 018017 e = PV x (1+i)^t
N (d2) = 057149 PV = e (1+i)^t
PV = e ^-itC = 1370
2 BLACK-SCHOLES OPTION VALUATION METHOD BS - PUT OPTION
A B C D E F G Compound at e
32
33 INPUT OUTPUT Face Value 100$
34 Interest 10
35 Standard Deviation (σ) = 05 d1 = 0430 Years 10
36 Expiration (in years) (T) = 025 d2 = 0180
37 Risk-Free Rate (Annual) (i) = 01 N(d1) = 0666 Description Compound FV
38 Stock Price (S ) = 100 N(d2) = 0571 Annual 1 25937425
39 Exercise Price (X) = 95 Semi 2 26532977
40 Dividend Yield (annual) (δ) = 0 P = 63497 Quarterly 4 26850638
Monthly 12 27070415
Daily 365 27179096
LONG CALCULATION (Break Down Approach) Hourly 8760 27182663
D1 = Ln ( S X ) ( i-δ+σ^2 2 ) σradict By Minute 525600 27182816
D1 = 0051293294 005625 025 By Second 31536000 27182819
Infinite e 27182818
D1 = 0430173178
N (d1) = 0666465164
PV calculation using e
D2= 0180173178 e = PV x (1+i)^t
N (d2) = 0571491692 PV = e (1+i)^t
PV = e ^-itP = 63497
3 PUT-CALL PARITY METHOD FOR CALCULATING THE PUT OPTION KNOWING THE CALL PRICE (same data as above)
C - P = S - X e -it
P = Xe -it - S + C
P = 63497
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
8
Review ndash Options
C = S e -δT
N (d1) ndash X e ndashiT
N (d2)
P = X e ndashiT
(1- N (d2)) ndash S e -δT
(1 - N (d1))
Volatility is the question on the BS ndashwhich assumes constant SD throughout the exercise
period - The time series of implied volatility
THE PUT ndash CALL PARITY RELATIONSHIP
Put prices can be derived simply from the prices of call
European Put or Call options are linked together in an equation known as the Put-
Call parity relationship
St lt= X St gt X
Payoff of Call Held 0 St - X
Payoff of Put Written -(X ndash St) 0
Total St ndash X St ndash X
PV (x) = X e ndashrt
The option has a payoff identical to that of the leveraged equity position the costs of
establishing them must be equal
C ndash P Cost of Call purchased = Premium received from Put written
The leverage Equity position requires a net cash outlay of S ndash X e ndashrt
the Cost
of the stock less the process from borrowing
C ndash P = S ndash X e ndashrt
PUT-CALL Parity Relationship - proper relationship
between Call and Put
Example 163
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
9
S = $110
C = $14 for 6 months with X = $105
P = $5 for 6 months with X=$105
rf = 50 (continuously compounding at e )
Assumptions
C ndash P = S ndash X e ndashrT
14 ndash 5 = 110 ndash 105 e ndash 05 x 05
9 = 759
This a violation of parityhellip Indicates mispricing and leads to Arbitrage
Opportunity
You can buy relatively cheap portfolio (buy the stock plus borrowing position
represented on the right side of the equation and sell the expensive portfolio
STRATEGY ndash In six months the stock will be worth Sr so you borrow PV of X
($105) and pay back the loan with interest resulting in cash outflow of $105
Sr ndash 105 writing the call if Sr exceeds 105
Purchase Puts will pay 105 ndash Sr if the stock is below the $105
Strategy Immediate
CF
CF if
Sr lt 105
CF if
Sr gt 105
1 Buy Stock -11000 Sr Sr
2 Borrow Xe ndashiT
= $10241 +10241 -105 -105
3 Sell Call 1400 0 -(Sr ndash 105)
4 Buy Call -500 105 ndash Sr 0
141 0 0
Whish is the difference of between 900 and 759 ndash riskless return
This applies if No dividends and under the European option
If Dividend then
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
10
P = C ndash S + PV (X) + PV ( Dividend) hellip Representing that the Dividend (δ) is
paid during the life of the option
Example
Using the IBM example ndash today is February 6
X = $100 (March calls)
T = 42 days
C = $280
P = $647
S = 9614
I = 20
δ = 0
P = C ndash S + PV (X) + PV ( Dividend) or P = C + PV (X) ndash S + PV (δ)
647 = 280 + 100 (1+002)42365
- 9614 + 0
647 = 663 is not that valuable to go after the reprising arbitrage
PUT OPTION VALUATION
P = X e ndashiT
(1- N (d2)) ndash S e -δT
(1 - N (d1))
Using the data from previous example
P = 95 e ndash 10x25
(1 ndash 005714) ndash 100 (1 ndash 06664)
P = 635
PUT-CALL Parity
P = C + PV (X) ndash So + PV (Div)
P = 1370 + 95 e -10 X 025
ndash 100 + 0
Hedge Ratios amp the BS format
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
11
The Hedge ratio is commonly called the Option Delta Is the change in the price
of call option for $1 increased in the stock price
This is the slope of value function evaluated at the current stock price
For Example
Slope of the curve at S = $120 equals 60 As the stock increases by $1 the option
increase on 060
For every Call Option Written 60 shares of stock would be needed to hedge the
Investment portfolio
For example if one writes 10 options and holds 6 shares of stock
H = 60 helliphelliphellip a $1 increase in stock will result $6 gain ($1x 6 shares) and with
the loss of $6 on 10 options written (10 x $060)
The Hedge Ratio for a Call is N (d1)
with the hedge ratio for a Put [N (d1) ndash 1]
N (d) is the area under standard deviation (normal)
Therefore the Call option Hedge Ratio must be positive and less than 10
And the Put option Hedge Ratio is negative and less than 10
Example 165
2 Portfolios
Portfolio A B
BUY 750 IBM Calls
200 Shares of IBM
800 shares of IBM
Which portfolio has a greater dollar exposure to IBM price movement
Using the Hedge ratio you could answer that question
Each Option change in value by H dollars for each $1 change in stock price
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
12
If H = 06 then 750 options = equivalent 450 shares (06 x 750)
Portfolio A = 450 equivalent + 200 shares which is less than Portfolio B with 800
shares
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
2
BLACK-SHOLES OPTION PRICING MODEL
The BlackndashScholes model is a mathematical description of financial markets and
derivative investment instruments The model develops partial differential equations
whose solution the BlackndashScholes formula is widely used in the pricing of European-
style options
Black-Scholes Model - Definition
A mathematical formula designed to price an option as a function of certain variables-
generally stock price striking price volatility time to expiration dividends to be paid
and the current risk-free interest rate
Black-Scholes Model - Introduction
The Black-Scholes model is a tool for equity options pricing Prior to the development of
the Black-Scholes Model there was no standard options pricing method and nobody can
put a fair price to charge for options The Black-Scholes Model turned that guessing
game into a mathematical science which helped develop the options market into the
lucrative industry it is today Options traders compare the prevailing option price in the
exchange against the theoretical value derived by the Black-Scholes Model in order to
determine if a particular option contract is over or under valued hence assisting them in
their options trading decision The Black-Scholes Model was originally created for the
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
3
pricing and hedging of European Call and Put options as the American Options market
the CBOE started only 1 month before the creation of the Black-Scholes Model The
difference in the pricing of European options and American options is that options
pricing of European options do not take into consideration the possibility of early
exercising American options therefore command a higher price than European options
due to the flexibility to exercise the option at anytime The classic Black-Scholes Model
does not take this extra value into consideration in its calculations
Black-Scholes Model Assumptions
There are several assumptions underlying the Black-Scholes model of calculating options
pricing The most significant is that volatility a measure of how much a stock can be
expected to move in the near-term is a constant over time The Black-Scholes model also
assumes stocks move in a manner referred to as a random walk at any given moment
they are as likely to move up as they are to move down These assumptions are combined
with the principle that options pricing should provide no immediate gain to either seller
or buyer
The exact 6 assumptions of the Black-Scholes Model are
1 Stock pays no dividends
2 Option can only be exercised upon expiration
3 Market direction cannot be predicted hence Random Walk
4 No commissions are charged in the transaction
5 Interest rates remain constant
6 Stock returns are normally distributed thus volatility is constant over time
As you can see the validity of many of these assumptions used by the Black-Scholes
Model is questionable or invalid resulting in theoretical values which are not always
accurate Hence theoretical values derived from the Black-Scholes Model are only good
as a guide for relative comparison and is not an exact indication to the over or under
priced nature of a stock option
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
4
Model assumptions
The BlackndashScholes model of the market for a particular equity makes the following
explicit assumptions
It is possible to borrow and lend cash at a known constant risk-free interest rate
This restriction has been removed in later extensions of the model
The price follows a Geometric Brownian motion with constant drift and volatility
It follows from this that the return is a Log-normal distribution This often implies
the validity of the efficient-market hypothesis
There are no transaction costs or taxes
The stock does not pay a dividend (see below for extensions to handle dividend
payments)
All securities are perfectly divisible (ie it is possible to buy any fraction of a
share)
There are no restrictions on short selling
There is no arbitrage opportunity
Options use the European exercise terms which dictate that options may only be
exercised on the day of expiration
From these conditions in the market for an equity (and for an option on the equity) the
authors show that it is possible to create a hedged position consisting of a long position
in the stock and a short position in [calls on the same stock] whose value will not depend
on the price of the stock[3]
Several of these assumptions of the original model have been removed in subsequent
extensions of the model Modern versions account for changing interest rates (Merton
1976) transaction costs and taxes (Ingerson 1976) and dividend payout (Merton 1973)
The Black Scholes formula calculates the price of European put and call options It can
be obtained by solving the BlackndashScholes partial differential equation
The value of a call option in terms of the BlackndashScholes parameters is
C (St) = SN (d1) ndash Xe ndashr(T-t)
N(d2)
d1 = [ ln (SoX) + (r + σ2 2) (T ndash t) ] [ σ SQR of (T ndash t) ]
d2 = d1 ndash σ SQRT of (T ndash t)
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
5
The price of a put option is
P (S t) = Xe ndashr(T-t) ndash S+(SN(d1) ndash Xe ndashr(T-t) N(d2)) = Xe ndashr(T-t) ndash S+C (St)
For both as above
N(bull) is the cumulative distribution function of the standard normal distribution
T - t is the time to maturity
S is the spot price of the underlying asset
X is the strike price
r is the risk free rate (annual rate expressed in terms of continuous compounding)
σ is the volatility in the log-returns of the underlying
Interpretation
N(d1) and N(d2) are the probabilities of the option expiring in-the-money under the
equivalent exponential martingale probability measure (numeacuteraire = stock) and the
equivalent martingale probability measure (numeacuteraire = risk free asset) respectively The
equivalent martingale probability measure is also called the risk-neutral probability
measure Note that both of these are probabilities in a measure theoretic sense and
neither of these is the true probability of expiring in-the-money under the real probability
measure In order to calculate the probability under the real (physical) probability
measure additional information is require
dmdashthe drift term in the physical measure or equivalently the market price of risk
Example
Suppose you want to value a call option under the following circumstances
Stock Price S0 = 100
Exercise Price X=95
Interest Rate r= 10
Dividend Yield δ = 0
Time to expiration T = 25 (one-quarter year)
Standard Deviation σ = 50
First calculate
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
6
d1 = [ln (10095) + (10-0 + 522)25] [ 5 SQRT of 25] = 43
d2 = 43 - 5 SQRT of 25 = 18
Next find N (d1) and d N(d2) The normal distribution function is tabulated and may be
found in many statistics books A table of N (d) is provided as Table 162 in the book
page 521 The normal distribution function N(d) is also provided in any spreadsheet
program In Excel the function name is NORMSDIST so using EXCEL (using
interpolation for 43) we find that
N(43) = 6664
N(18) = 5714
Finally remember that with dividends (δ) = o
S0 e ndash δT
= S0
Thus the value of the call option is
C = 100 x 6664 ndash 95e -10x025
x 5714
=6664 ndash 5294 = $1370
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
7
BLACK-SCHOLES OPTION VALUATION METHOD BS - CALL OPTION
A B C D E F G Compound at e
5
6 INPUT OUTPUT Face Value 100$
7 Interest 10
8 Standard Deviation (σ) = 05 d1 = 0430 Years 109 Expiration (in years) (T) = 025 d2 = 0180
10 Risk-Free Rate (Annual) (i) = 01 N(d1) = 0666 Description Compound FV
11 Stock Price (S ) = 100 N(d2) = 0571 Annual 1 25937425 12 Exercise Price (X) = 95 Semi 2 26532977
13 Dividend Yield (annual) (δ) = 0 C = 136953 Quarterly 4 26850638 Monthly 12 27070415
Daily 365 27179096
LONG CALCULATION (Break Down Approach) Hourly 8760 27182663
D1 = Ln ( S X ) ( i-δ+σ^2 2 ) σradict By Minute 525600 27182816 D1 = 0051293294 005625 025 By Second 31536000 27182819
Infinite e 27182818
D1 = 043017
N (d1) = 066647
PV calculation using e
D2= 018017 e = PV x (1+i)^t
N (d2) = 057149 PV = e (1+i)^t
PV = e ^-itC = 1370
2 BLACK-SCHOLES OPTION VALUATION METHOD BS - PUT OPTION
A B C D E F G Compound at e
32
33 INPUT OUTPUT Face Value 100$
34 Interest 10
35 Standard Deviation (σ) = 05 d1 = 0430 Years 10
36 Expiration (in years) (T) = 025 d2 = 0180
37 Risk-Free Rate (Annual) (i) = 01 N(d1) = 0666 Description Compound FV
38 Stock Price (S ) = 100 N(d2) = 0571 Annual 1 25937425
39 Exercise Price (X) = 95 Semi 2 26532977
40 Dividend Yield (annual) (δ) = 0 P = 63497 Quarterly 4 26850638
Monthly 12 27070415
Daily 365 27179096
LONG CALCULATION (Break Down Approach) Hourly 8760 27182663
D1 = Ln ( S X ) ( i-δ+σ^2 2 ) σradict By Minute 525600 27182816
D1 = 0051293294 005625 025 By Second 31536000 27182819
Infinite e 27182818
D1 = 0430173178
N (d1) = 0666465164
PV calculation using e
D2= 0180173178 e = PV x (1+i)^t
N (d2) = 0571491692 PV = e (1+i)^t
PV = e ^-itP = 63497
3 PUT-CALL PARITY METHOD FOR CALCULATING THE PUT OPTION KNOWING THE CALL PRICE (same data as above)
C - P = S - X e -it
P = Xe -it - S + C
P = 63497
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
8
Review ndash Options
C = S e -δT
N (d1) ndash X e ndashiT
N (d2)
P = X e ndashiT
(1- N (d2)) ndash S e -δT
(1 - N (d1))
Volatility is the question on the BS ndashwhich assumes constant SD throughout the exercise
period - The time series of implied volatility
THE PUT ndash CALL PARITY RELATIONSHIP
Put prices can be derived simply from the prices of call
European Put or Call options are linked together in an equation known as the Put-
Call parity relationship
St lt= X St gt X
Payoff of Call Held 0 St - X
Payoff of Put Written -(X ndash St) 0
Total St ndash X St ndash X
PV (x) = X e ndashrt
The option has a payoff identical to that of the leveraged equity position the costs of
establishing them must be equal
C ndash P Cost of Call purchased = Premium received from Put written
The leverage Equity position requires a net cash outlay of S ndash X e ndashrt
the Cost
of the stock less the process from borrowing
C ndash P = S ndash X e ndashrt
PUT-CALL Parity Relationship - proper relationship
between Call and Put
Example 163
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
9
S = $110
C = $14 for 6 months with X = $105
P = $5 for 6 months with X=$105
rf = 50 (continuously compounding at e )
Assumptions
C ndash P = S ndash X e ndashrT
14 ndash 5 = 110 ndash 105 e ndash 05 x 05
9 = 759
This a violation of parityhellip Indicates mispricing and leads to Arbitrage
Opportunity
You can buy relatively cheap portfolio (buy the stock plus borrowing position
represented on the right side of the equation and sell the expensive portfolio
STRATEGY ndash In six months the stock will be worth Sr so you borrow PV of X
($105) and pay back the loan with interest resulting in cash outflow of $105
Sr ndash 105 writing the call if Sr exceeds 105
Purchase Puts will pay 105 ndash Sr if the stock is below the $105
Strategy Immediate
CF
CF if
Sr lt 105
CF if
Sr gt 105
1 Buy Stock -11000 Sr Sr
2 Borrow Xe ndashiT
= $10241 +10241 -105 -105
3 Sell Call 1400 0 -(Sr ndash 105)
4 Buy Call -500 105 ndash Sr 0
141 0 0
Whish is the difference of between 900 and 759 ndash riskless return
This applies if No dividends and under the European option
If Dividend then
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
10
P = C ndash S + PV (X) + PV ( Dividend) hellip Representing that the Dividend (δ) is
paid during the life of the option
Example
Using the IBM example ndash today is February 6
X = $100 (March calls)
T = 42 days
C = $280
P = $647
S = 9614
I = 20
δ = 0
P = C ndash S + PV (X) + PV ( Dividend) or P = C + PV (X) ndash S + PV (δ)
647 = 280 + 100 (1+002)42365
- 9614 + 0
647 = 663 is not that valuable to go after the reprising arbitrage
PUT OPTION VALUATION
P = X e ndashiT
(1- N (d2)) ndash S e -δT
(1 - N (d1))
Using the data from previous example
P = 95 e ndash 10x25
(1 ndash 005714) ndash 100 (1 ndash 06664)
P = 635
PUT-CALL Parity
P = C + PV (X) ndash So + PV (Div)
P = 1370 + 95 e -10 X 025
ndash 100 + 0
Hedge Ratios amp the BS format
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
11
The Hedge ratio is commonly called the Option Delta Is the change in the price
of call option for $1 increased in the stock price
This is the slope of value function evaluated at the current stock price
For Example
Slope of the curve at S = $120 equals 60 As the stock increases by $1 the option
increase on 060
For every Call Option Written 60 shares of stock would be needed to hedge the
Investment portfolio
For example if one writes 10 options and holds 6 shares of stock
H = 60 helliphelliphellip a $1 increase in stock will result $6 gain ($1x 6 shares) and with
the loss of $6 on 10 options written (10 x $060)
The Hedge Ratio for a Call is N (d1)
with the hedge ratio for a Put [N (d1) ndash 1]
N (d) is the area under standard deviation (normal)
Therefore the Call option Hedge Ratio must be positive and less than 10
And the Put option Hedge Ratio is negative and less than 10
Example 165
2 Portfolios
Portfolio A B
BUY 750 IBM Calls
200 Shares of IBM
800 shares of IBM
Which portfolio has a greater dollar exposure to IBM price movement
Using the Hedge ratio you could answer that question
Each Option change in value by H dollars for each $1 change in stock price
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
12
If H = 06 then 750 options = equivalent 450 shares (06 x 750)
Portfolio A = 450 equivalent + 200 shares which is less than Portfolio B with 800
shares
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
3
pricing and hedging of European Call and Put options as the American Options market
the CBOE started only 1 month before the creation of the Black-Scholes Model The
difference in the pricing of European options and American options is that options
pricing of European options do not take into consideration the possibility of early
exercising American options therefore command a higher price than European options
due to the flexibility to exercise the option at anytime The classic Black-Scholes Model
does not take this extra value into consideration in its calculations
Black-Scholes Model Assumptions
There are several assumptions underlying the Black-Scholes model of calculating options
pricing The most significant is that volatility a measure of how much a stock can be
expected to move in the near-term is a constant over time The Black-Scholes model also
assumes stocks move in a manner referred to as a random walk at any given moment
they are as likely to move up as they are to move down These assumptions are combined
with the principle that options pricing should provide no immediate gain to either seller
or buyer
The exact 6 assumptions of the Black-Scholes Model are
1 Stock pays no dividends
2 Option can only be exercised upon expiration
3 Market direction cannot be predicted hence Random Walk
4 No commissions are charged in the transaction
5 Interest rates remain constant
6 Stock returns are normally distributed thus volatility is constant over time
As you can see the validity of many of these assumptions used by the Black-Scholes
Model is questionable or invalid resulting in theoretical values which are not always
accurate Hence theoretical values derived from the Black-Scholes Model are only good
as a guide for relative comparison and is not an exact indication to the over or under
priced nature of a stock option
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
4
Model assumptions
The BlackndashScholes model of the market for a particular equity makes the following
explicit assumptions
It is possible to borrow and lend cash at a known constant risk-free interest rate
This restriction has been removed in later extensions of the model
The price follows a Geometric Brownian motion with constant drift and volatility
It follows from this that the return is a Log-normal distribution This often implies
the validity of the efficient-market hypothesis
There are no transaction costs or taxes
The stock does not pay a dividend (see below for extensions to handle dividend
payments)
All securities are perfectly divisible (ie it is possible to buy any fraction of a
share)
There are no restrictions on short selling
There is no arbitrage opportunity
Options use the European exercise terms which dictate that options may only be
exercised on the day of expiration
From these conditions in the market for an equity (and for an option on the equity) the
authors show that it is possible to create a hedged position consisting of a long position
in the stock and a short position in [calls on the same stock] whose value will not depend
on the price of the stock[3]
Several of these assumptions of the original model have been removed in subsequent
extensions of the model Modern versions account for changing interest rates (Merton
1976) transaction costs and taxes (Ingerson 1976) and dividend payout (Merton 1973)
The Black Scholes formula calculates the price of European put and call options It can
be obtained by solving the BlackndashScholes partial differential equation
The value of a call option in terms of the BlackndashScholes parameters is
C (St) = SN (d1) ndash Xe ndashr(T-t)
N(d2)
d1 = [ ln (SoX) + (r + σ2 2) (T ndash t) ] [ σ SQR of (T ndash t) ]
d2 = d1 ndash σ SQRT of (T ndash t)
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
5
The price of a put option is
P (S t) = Xe ndashr(T-t) ndash S+(SN(d1) ndash Xe ndashr(T-t) N(d2)) = Xe ndashr(T-t) ndash S+C (St)
For both as above
N(bull) is the cumulative distribution function of the standard normal distribution
T - t is the time to maturity
S is the spot price of the underlying asset
X is the strike price
r is the risk free rate (annual rate expressed in terms of continuous compounding)
σ is the volatility in the log-returns of the underlying
Interpretation
N(d1) and N(d2) are the probabilities of the option expiring in-the-money under the
equivalent exponential martingale probability measure (numeacuteraire = stock) and the
equivalent martingale probability measure (numeacuteraire = risk free asset) respectively The
equivalent martingale probability measure is also called the risk-neutral probability
measure Note that both of these are probabilities in a measure theoretic sense and
neither of these is the true probability of expiring in-the-money under the real probability
measure In order to calculate the probability under the real (physical) probability
measure additional information is require
dmdashthe drift term in the physical measure or equivalently the market price of risk
Example
Suppose you want to value a call option under the following circumstances
Stock Price S0 = 100
Exercise Price X=95
Interest Rate r= 10
Dividend Yield δ = 0
Time to expiration T = 25 (one-quarter year)
Standard Deviation σ = 50
First calculate
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
6
d1 = [ln (10095) + (10-0 + 522)25] [ 5 SQRT of 25] = 43
d2 = 43 - 5 SQRT of 25 = 18
Next find N (d1) and d N(d2) The normal distribution function is tabulated and may be
found in many statistics books A table of N (d) is provided as Table 162 in the book
page 521 The normal distribution function N(d) is also provided in any spreadsheet
program In Excel the function name is NORMSDIST so using EXCEL (using
interpolation for 43) we find that
N(43) = 6664
N(18) = 5714
Finally remember that with dividends (δ) = o
S0 e ndash δT
= S0
Thus the value of the call option is
C = 100 x 6664 ndash 95e -10x025
x 5714
=6664 ndash 5294 = $1370
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
7
BLACK-SCHOLES OPTION VALUATION METHOD BS - CALL OPTION
A B C D E F G Compound at e
5
6 INPUT OUTPUT Face Value 100$
7 Interest 10
8 Standard Deviation (σ) = 05 d1 = 0430 Years 109 Expiration (in years) (T) = 025 d2 = 0180
10 Risk-Free Rate (Annual) (i) = 01 N(d1) = 0666 Description Compound FV
11 Stock Price (S ) = 100 N(d2) = 0571 Annual 1 25937425 12 Exercise Price (X) = 95 Semi 2 26532977
13 Dividend Yield (annual) (δ) = 0 C = 136953 Quarterly 4 26850638 Monthly 12 27070415
Daily 365 27179096
LONG CALCULATION (Break Down Approach) Hourly 8760 27182663
D1 = Ln ( S X ) ( i-δ+σ^2 2 ) σradict By Minute 525600 27182816 D1 = 0051293294 005625 025 By Second 31536000 27182819
Infinite e 27182818
D1 = 043017
N (d1) = 066647
PV calculation using e
D2= 018017 e = PV x (1+i)^t
N (d2) = 057149 PV = e (1+i)^t
PV = e ^-itC = 1370
2 BLACK-SCHOLES OPTION VALUATION METHOD BS - PUT OPTION
A B C D E F G Compound at e
32
33 INPUT OUTPUT Face Value 100$
34 Interest 10
35 Standard Deviation (σ) = 05 d1 = 0430 Years 10
36 Expiration (in years) (T) = 025 d2 = 0180
37 Risk-Free Rate (Annual) (i) = 01 N(d1) = 0666 Description Compound FV
38 Stock Price (S ) = 100 N(d2) = 0571 Annual 1 25937425
39 Exercise Price (X) = 95 Semi 2 26532977
40 Dividend Yield (annual) (δ) = 0 P = 63497 Quarterly 4 26850638
Monthly 12 27070415
Daily 365 27179096
LONG CALCULATION (Break Down Approach) Hourly 8760 27182663
D1 = Ln ( S X ) ( i-δ+σ^2 2 ) σradict By Minute 525600 27182816
D1 = 0051293294 005625 025 By Second 31536000 27182819
Infinite e 27182818
D1 = 0430173178
N (d1) = 0666465164
PV calculation using e
D2= 0180173178 e = PV x (1+i)^t
N (d2) = 0571491692 PV = e (1+i)^t
PV = e ^-itP = 63497
3 PUT-CALL PARITY METHOD FOR CALCULATING THE PUT OPTION KNOWING THE CALL PRICE (same data as above)
C - P = S - X e -it
P = Xe -it - S + C
P = 63497
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
8
Review ndash Options
C = S e -δT
N (d1) ndash X e ndashiT
N (d2)
P = X e ndashiT
(1- N (d2)) ndash S e -δT
(1 - N (d1))
Volatility is the question on the BS ndashwhich assumes constant SD throughout the exercise
period - The time series of implied volatility
THE PUT ndash CALL PARITY RELATIONSHIP
Put prices can be derived simply from the prices of call
European Put or Call options are linked together in an equation known as the Put-
Call parity relationship
St lt= X St gt X
Payoff of Call Held 0 St - X
Payoff of Put Written -(X ndash St) 0
Total St ndash X St ndash X
PV (x) = X e ndashrt
The option has a payoff identical to that of the leveraged equity position the costs of
establishing them must be equal
C ndash P Cost of Call purchased = Premium received from Put written
The leverage Equity position requires a net cash outlay of S ndash X e ndashrt
the Cost
of the stock less the process from borrowing
C ndash P = S ndash X e ndashrt
PUT-CALL Parity Relationship - proper relationship
between Call and Put
Example 163
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
9
S = $110
C = $14 for 6 months with X = $105
P = $5 for 6 months with X=$105
rf = 50 (continuously compounding at e )
Assumptions
C ndash P = S ndash X e ndashrT
14 ndash 5 = 110 ndash 105 e ndash 05 x 05
9 = 759
This a violation of parityhellip Indicates mispricing and leads to Arbitrage
Opportunity
You can buy relatively cheap portfolio (buy the stock plus borrowing position
represented on the right side of the equation and sell the expensive portfolio
STRATEGY ndash In six months the stock will be worth Sr so you borrow PV of X
($105) and pay back the loan with interest resulting in cash outflow of $105
Sr ndash 105 writing the call if Sr exceeds 105
Purchase Puts will pay 105 ndash Sr if the stock is below the $105
Strategy Immediate
CF
CF if
Sr lt 105
CF if
Sr gt 105
1 Buy Stock -11000 Sr Sr
2 Borrow Xe ndashiT
= $10241 +10241 -105 -105
3 Sell Call 1400 0 -(Sr ndash 105)
4 Buy Call -500 105 ndash Sr 0
141 0 0
Whish is the difference of between 900 and 759 ndash riskless return
This applies if No dividends and under the European option
If Dividend then
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
10
P = C ndash S + PV (X) + PV ( Dividend) hellip Representing that the Dividend (δ) is
paid during the life of the option
Example
Using the IBM example ndash today is February 6
X = $100 (March calls)
T = 42 days
C = $280
P = $647
S = 9614
I = 20
δ = 0
P = C ndash S + PV (X) + PV ( Dividend) or P = C + PV (X) ndash S + PV (δ)
647 = 280 + 100 (1+002)42365
- 9614 + 0
647 = 663 is not that valuable to go after the reprising arbitrage
PUT OPTION VALUATION
P = X e ndashiT
(1- N (d2)) ndash S e -δT
(1 - N (d1))
Using the data from previous example
P = 95 e ndash 10x25
(1 ndash 005714) ndash 100 (1 ndash 06664)
P = 635
PUT-CALL Parity
P = C + PV (X) ndash So + PV (Div)
P = 1370 + 95 e -10 X 025
ndash 100 + 0
Hedge Ratios amp the BS format
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
11
The Hedge ratio is commonly called the Option Delta Is the change in the price
of call option for $1 increased in the stock price
This is the slope of value function evaluated at the current stock price
For Example
Slope of the curve at S = $120 equals 60 As the stock increases by $1 the option
increase on 060
For every Call Option Written 60 shares of stock would be needed to hedge the
Investment portfolio
For example if one writes 10 options and holds 6 shares of stock
H = 60 helliphelliphellip a $1 increase in stock will result $6 gain ($1x 6 shares) and with
the loss of $6 on 10 options written (10 x $060)
The Hedge Ratio for a Call is N (d1)
with the hedge ratio for a Put [N (d1) ndash 1]
N (d) is the area under standard deviation (normal)
Therefore the Call option Hedge Ratio must be positive and less than 10
And the Put option Hedge Ratio is negative and less than 10
Example 165
2 Portfolios
Portfolio A B
BUY 750 IBM Calls
200 Shares of IBM
800 shares of IBM
Which portfolio has a greater dollar exposure to IBM price movement
Using the Hedge ratio you could answer that question
Each Option change in value by H dollars for each $1 change in stock price
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
12
If H = 06 then 750 options = equivalent 450 shares (06 x 750)
Portfolio A = 450 equivalent + 200 shares which is less than Portfolio B with 800
shares
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
4
Model assumptions
The BlackndashScholes model of the market for a particular equity makes the following
explicit assumptions
It is possible to borrow and lend cash at a known constant risk-free interest rate
This restriction has been removed in later extensions of the model
The price follows a Geometric Brownian motion with constant drift and volatility
It follows from this that the return is a Log-normal distribution This often implies
the validity of the efficient-market hypothesis
There are no transaction costs or taxes
The stock does not pay a dividend (see below for extensions to handle dividend
payments)
All securities are perfectly divisible (ie it is possible to buy any fraction of a
share)
There are no restrictions on short selling
There is no arbitrage opportunity
Options use the European exercise terms which dictate that options may only be
exercised on the day of expiration
From these conditions in the market for an equity (and for an option on the equity) the
authors show that it is possible to create a hedged position consisting of a long position
in the stock and a short position in [calls on the same stock] whose value will not depend
on the price of the stock[3]
Several of these assumptions of the original model have been removed in subsequent
extensions of the model Modern versions account for changing interest rates (Merton
1976) transaction costs and taxes (Ingerson 1976) and dividend payout (Merton 1973)
The Black Scholes formula calculates the price of European put and call options It can
be obtained by solving the BlackndashScholes partial differential equation
The value of a call option in terms of the BlackndashScholes parameters is
C (St) = SN (d1) ndash Xe ndashr(T-t)
N(d2)
d1 = [ ln (SoX) + (r + σ2 2) (T ndash t) ] [ σ SQR of (T ndash t) ]
d2 = d1 ndash σ SQRT of (T ndash t)
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
5
The price of a put option is
P (S t) = Xe ndashr(T-t) ndash S+(SN(d1) ndash Xe ndashr(T-t) N(d2)) = Xe ndashr(T-t) ndash S+C (St)
For both as above
N(bull) is the cumulative distribution function of the standard normal distribution
T - t is the time to maturity
S is the spot price of the underlying asset
X is the strike price
r is the risk free rate (annual rate expressed in terms of continuous compounding)
σ is the volatility in the log-returns of the underlying
Interpretation
N(d1) and N(d2) are the probabilities of the option expiring in-the-money under the
equivalent exponential martingale probability measure (numeacuteraire = stock) and the
equivalent martingale probability measure (numeacuteraire = risk free asset) respectively The
equivalent martingale probability measure is also called the risk-neutral probability
measure Note that both of these are probabilities in a measure theoretic sense and
neither of these is the true probability of expiring in-the-money under the real probability
measure In order to calculate the probability under the real (physical) probability
measure additional information is require
dmdashthe drift term in the physical measure or equivalently the market price of risk
Example
Suppose you want to value a call option under the following circumstances
Stock Price S0 = 100
Exercise Price X=95
Interest Rate r= 10
Dividend Yield δ = 0
Time to expiration T = 25 (one-quarter year)
Standard Deviation σ = 50
First calculate
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
6
d1 = [ln (10095) + (10-0 + 522)25] [ 5 SQRT of 25] = 43
d2 = 43 - 5 SQRT of 25 = 18
Next find N (d1) and d N(d2) The normal distribution function is tabulated and may be
found in many statistics books A table of N (d) is provided as Table 162 in the book
page 521 The normal distribution function N(d) is also provided in any spreadsheet
program In Excel the function name is NORMSDIST so using EXCEL (using
interpolation for 43) we find that
N(43) = 6664
N(18) = 5714
Finally remember that with dividends (δ) = o
S0 e ndash δT
= S0
Thus the value of the call option is
C = 100 x 6664 ndash 95e -10x025
x 5714
=6664 ndash 5294 = $1370
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
7
BLACK-SCHOLES OPTION VALUATION METHOD BS - CALL OPTION
A B C D E F G Compound at e
5
6 INPUT OUTPUT Face Value 100$
7 Interest 10
8 Standard Deviation (σ) = 05 d1 = 0430 Years 109 Expiration (in years) (T) = 025 d2 = 0180
10 Risk-Free Rate (Annual) (i) = 01 N(d1) = 0666 Description Compound FV
11 Stock Price (S ) = 100 N(d2) = 0571 Annual 1 25937425 12 Exercise Price (X) = 95 Semi 2 26532977
13 Dividend Yield (annual) (δ) = 0 C = 136953 Quarterly 4 26850638 Monthly 12 27070415
Daily 365 27179096
LONG CALCULATION (Break Down Approach) Hourly 8760 27182663
D1 = Ln ( S X ) ( i-δ+σ^2 2 ) σradict By Minute 525600 27182816 D1 = 0051293294 005625 025 By Second 31536000 27182819
Infinite e 27182818
D1 = 043017
N (d1) = 066647
PV calculation using e
D2= 018017 e = PV x (1+i)^t
N (d2) = 057149 PV = e (1+i)^t
PV = e ^-itC = 1370
2 BLACK-SCHOLES OPTION VALUATION METHOD BS - PUT OPTION
A B C D E F G Compound at e
32
33 INPUT OUTPUT Face Value 100$
34 Interest 10
35 Standard Deviation (σ) = 05 d1 = 0430 Years 10
36 Expiration (in years) (T) = 025 d2 = 0180
37 Risk-Free Rate (Annual) (i) = 01 N(d1) = 0666 Description Compound FV
38 Stock Price (S ) = 100 N(d2) = 0571 Annual 1 25937425
39 Exercise Price (X) = 95 Semi 2 26532977
40 Dividend Yield (annual) (δ) = 0 P = 63497 Quarterly 4 26850638
Monthly 12 27070415
Daily 365 27179096
LONG CALCULATION (Break Down Approach) Hourly 8760 27182663
D1 = Ln ( S X ) ( i-δ+σ^2 2 ) σradict By Minute 525600 27182816
D1 = 0051293294 005625 025 By Second 31536000 27182819
Infinite e 27182818
D1 = 0430173178
N (d1) = 0666465164
PV calculation using e
D2= 0180173178 e = PV x (1+i)^t
N (d2) = 0571491692 PV = e (1+i)^t
PV = e ^-itP = 63497
3 PUT-CALL PARITY METHOD FOR CALCULATING THE PUT OPTION KNOWING THE CALL PRICE (same data as above)
C - P = S - X e -it
P = Xe -it - S + C
P = 63497
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
8
Review ndash Options
C = S e -δT
N (d1) ndash X e ndashiT
N (d2)
P = X e ndashiT
(1- N (d2)) ndash S e -δT
(1 - N (d1))
Volatility is the question on the BS ndashwhich assumes constant SD throughout the exercise
period - The time series of implied volatility
THE PUT ndash CALL PARITY RELATIONSHIP
Put prices can be derived simply from the prices of call
European Put or Call options are linked together in an equation known as the Put-
Call parity relationship
St lt= X St gt X
Payoff of Call Held 0 St - X
Payoff of Put Written -(X ndash St) 0
Total St ndash X St ndash X
PV (x) = X e ndashrt
The option has a payoff identical to that of the leveraged equity position the costs of
establishing them must be equal
C ndash P Cost of Call purchased = Premium received from Put written
The leverage Equity position requires a net cash outlay of S ndash X e ndashrt
the Cost
of the stock less the process from borrowing
C ndash P = S ndash X e ndashrt
PUT-CALL Parity Relationship - proper relationship
between Call and Put
Example 163
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
9
S = $110
C = $14 for 6 months with X = $105
P = $5 for 6 months with X=$105
rf = 50 (continuously compounding at e )
Assumptions
C ndash P = S ndash X e ndashrT
14 ndash 5 = 110 ndash 105 e ndash 05 x 05
9 = 759
This a violation of parityhellip Indicates mispricing and leads to Arbitrage
Opportunity
You can buy relatively cheap portfolio (buy the stock plus borrowing position
represented on the right side of the equation and sell the expensive portfolio
STRATEGY ndash In six months the stock will be worth Sr so you borrow PV of X
($105) and pay back the loan with interest resulting in cash outflow of $105
Sr ndash 105 writing the call if Sr exceeds 105
Purchase Puts will pay 105 ndash Sr if the stock is below the $105
Strategy Immediate
CF
CF if
Sr lt 105
CF if
Sr gt 105
1 Buy Stock -11000 Sr Sr
2 Borrow Xe ndashiT
= $10241 +10241 -105 -105
3 Sell Call 1400 0 -(Sr ndash 105)
4 Buy Call -500 105 ndash Sr 0
141 0 0
Whish is the difference of between 900 and 759 ndash riskless return
This applies if No dividends and under the European option
If Dividend then
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
10
P = C ndash S + PV (X) + PV ( Dividend) hellip Representing that the Dividend (δ) is
paid during the life of the option
Example
Using the IBM example ndash today is February 6
X = $100 (March calls)
T = 42 days
C = $280
P = $647
S = 9614
I = 20
δ = 0
P = C ndash S + PV (X) + PV ( Dividend) or P = C + PV (X) ndash S + PV (δ)
647 = 280 + 100 (1+002)42365
- 9614 + 0
647 = 663 is not that valuable to go after the reprising arbitrage
PUT OPTION VALUATION
P = X e ndashiT
(1- N (d2)) ndash S e -δT
(1 - N (d1))
Using the data from previous example
P = 95 e ndash 10x25
(1 ndash 005714) ndash 100 (1 ndash 06664)
P = 635
PUT-CALL Parity
P = C + PV (X) ndash So + PV (Div)
P = 1370 + 95 e -10 X 025
ndash 100 + 0
Hedge Ratios amp the BS format
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
11
The Hedge ratio is commonly called the Option Delta Is the change in the price
of call option for $1 increased in the stock price
This is the slope of value function evaluated at the current stock price
For Example
Slope of the curve at S = $120 equals 60 As the stock increases by $1 the option
increase on 060
For every Call Option Written 60 shares of stock would be needed to hedge the
Investment portfolio
For example if one writes 10 options and holds 6 shares of stock
H = 60 helliphelliphellip a $1 increase in stock will result $6 gain ($1x 6 shares) and with
the loss of $6 on 10 options written (10 x $060)
The Hedge Ratio for a Call is N (d1)
with the hedge ratio for a Put [N (d1) ndash 1]
N (d) is the area under standard deviation (normal)
Therefore the Call option Hedge Ratio must be positive and less than 10
And the Put option Hedge Ratio is negative and less than 10
Example 165
2 Portfolios
Portfolio A B
BUY 750 IBM Calls
200 Shares of IBM
800 shares of IBM
Which portfolio has a greater dollar exposure to IBM price movement
Using the Hedge ratio you could answer that question
Each Option change in value by H dollars for each $1 change in stock price
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
12
If H = 06 then 750 options = equivalent 450 shares (06 x 750)
Portfolio A = 450 equivalent + 200 shares which is less than Portfolio B with 800
shares
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
5
The price of a put option is
P (S t) = Xe ndashr(T-t) ndash S+(SN(d1) ndash Xe ndashr(T-t) N(d2)) = Xe ndashr(T-t) ndash S+C (St)
For both as above
N(bull) is the cumulative distribution function of the standard normal distribution
T - t is the time to maturity
S is the spot price of the underlying asset
X is the strike price
r is the risk free rate (annual rate expressed in terms of continuous compounding)
σ is the volatility in the log-returns of the underlying
Interpretation
N(d1) and N(d2) are the probabilities of the option expiring in-the-money under the
equivalent exponential martingale probability measure (numeacuteraire = stock) and the
equivalent martingale probability measure (numeacuteraire = risk free asset) respectively The
equivalent martingale probability measure is also called the risk-neutral probability
measure Note that both of these are probabilities in a measure theoretic sense and
neither of these is the true probability of expiring in-the-money under the real probability
measure In order to calculate the probability under the real (physical) probability
measure additional information is require
dmdashthe drift term in the physical measure or equivalently the market price of risk
Example
Suppose you want to value a call option under the following circumstances
Stock Price S0 = 100
Exercise Price X=95
Interest Rate r= 10
Dividend Yield δ = 0
Time to expiration T = 25 (one-quarter year)
Standard Deviation σ = 50
First calculate
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
6
d1 = [ln (10095) + (10-0 + 522)25] [ 5 SQRT of 25] = 43
d2 = 43 - 5 SQRT of 25 = 18
Next find N (d1) and d N(d2) The normal distribution function is tabulated and may be
found in many statistics books A table of N (d) is provided as Table 162 in the book
page 521 The normal distribution function N(d) is also provided in any spreadsheet
program In Excel the function name is NORMSDIST so using EXCEL (using
interpolation for 43) we find that
N(43) = 6664
N(18) = 5714
Finally remember that with dividends (δ) = o
S0 e ndash δT
= S0
Thus the value of the call option is
C = 100 x 6664 ndash 95e -10x025
x 5714
=6664 ndash 5294 = $1370
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
7
BLACK-SCHOLES OPTION VALUATION METHOD BS - CALL OPTION
A B C D E F G Compound at e
5
6 INPUT OUTPUT Face Value 100$
7 Interest 10
8 Standard Deviation (σ) = 05 d1 = 0430 Years 109 Expiration (in years) (T) = 025 d2 = 0180
10 Risk-Free Rate (Annual) (i) = 01 N(d1) = 0666 Description Compound FV
11 Stock Price (S ) = 100 N(d2) = 0571 Annual 1 25937425 12 Exercise Price (X) = 95 Semi 2 26532977
13 Dividend Yield (annual) (δ) = 0 C = 136953 Quarterly 4 26850638 Monthly 12 27070415
Daily 365 27179096
LONG CALCULATION (Break Down Approach) Hourly 8760 27182663
D1 = Ln ( S X ) ( i-δ+σ^2 2 ) σradict By Minute 525600 27182816 D1 = 0051293294 005625 025 By Second 31536000 27182819
Infinite e 27182818
D1 = 043017
N (d1) = 066647
PV calculation using e
D2= 018017 e = PV x (1+i)^t
N (d2) = 057149 PV = e (1+i)^t
PV = e ^-itC = 1370
2 BLACK-SCHOLES OPTION VALUATION METHOD BS - PUT OPTION
A B C D E F G Compound at e
32
33 INPUT OUTPUT Face Value 100$
34 Interest 10
35 Standard Deviation (σ) = 05 d1 = 0430 Years 10
36 Expiration (in years) (T) = 025 d2 = 0180
37 Risk-Free Rate (Annual) (i) = 01 N(d1) = 0666 Description Compound FV
38 Stock Price (S ) = 100 N(d2) = 0571 Annual 1 25937425
39 Exercise Price (X) = 95 Semi 2 26532977
40 Dividend Yield (annual) (δ) = 0 P = 63497 Quarterly 4 26850638
Monthly 12 27070415
Daily 365 27179096
LONG CALCULATION (Break Down Approach) Hourly 8760 27182663
D1 = Ln ( S X ) ( i-δ+σ^2 2 ) σradict By Minute 525600 27182816
D1 = 0051293294 005625 025 By Second 31536000 27182819
Infinite e 27182818
D1 = 0430173178
N (d1) = 0666465164
PV calculation using e
D2= 0180173178 e = PV x (1+i)^t
N (d2) = 0571491692 PV = e (1+i)^t
PV = e ^-itP = 63497
3 PUT-CALL PARITY METHOD FOR CALCULATING THE PUT OPTION KNOWING THE CALL PRICE (same data as above)
C - P = S - X e -it
P = Xe -it - S + C
P = 63497
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
8
Review ndash Options
C = S e -δT
N (d1) ndash X e ndashiT
N (d2)
P = X e ndashiT
(1- N (d2)) ndash S e -δT
(1 - N (d1))
Volatility is the question on the BS ndashwhich assumes constant SD throughout the exercise
period - The time series of implied volatility
THE PUT ndash CALL PARITY RELATIONSHIP
Put prices can be derived simply from the prices of call
European Put or Call options are linked together in an equation known as the Put-
Call parity relationship
St lt= X St gt X
Payoff of Call Held 0 St - X
Payoff of Put Written -(X ndash St) 0
Total St ndash X St ndash X
PV (x) = X e ndashrt
The option has a payoff identical to that of the leveraged equity position the costs of
establishing them must be equal
C ndash P Cost of Call purchased = Premium received from Put written
The leverage Equity position requires a net cash outlay of S ndash X e ndashrt
the Cost
of the stock less the process from borrowing
C ndash P = S ndash X e ndashrt
PUT-CALL Parity Relationship - proper relationship
between Call and Put
Example 163
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
9
S = $110
C = $14 for 6 months with X = $105
P = $5 for 6 months with X=$105
rf = 50 (continuously compounding at e )
Assumptions
C ndash P = S ndash X e ndashrT
14 ndash 5 = 110 ndash 105 e ndash 05 x 05
9 = 759
This a violation of parityhellip Indicates mispricing and leads to Arbitrage
Opportunity
You can buy relatively cheap portfolio (buy the stock plus borrowing position
represented on the right side of the equation and sell the expensive portfolio
STRATEGY ndash In six months the stock will be worth Sr so you borrow PV of X
($105) and pay back the loan with interest resulting in cash outflow of $105
Sr ndash 105 writing the call if Sr exceeds 105
Purchase Puts will pay 105 ndash Sr if the stock is below the $105
Strategy Immediate
CF
CF if
Sr lt 105
CF if
Sr gt 105
1 Buy Stock -11000 Sr Sr
2 Borrow Xe ndashiT
= $10241 +10241 -105 -105
3 Sell Call 1400 0 -(Sr ndash 105)
4 Buy Call -500 105 ndash Sr 0
141 0 0
Whish is the difference of between 900 and 759 ndash riskless return
This applies if No dividends and under the European option
If Dividend then
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
10
P = C ndash S + PV (X) + PV ( Dividend) hellip Representing that the Dividend (δ) is
paid during the life of the option
Example
Using the IBM example ndash today is February 6
X = $100 (March calls)
T = 42 days
C = $280
P = $647
S = 9614
I = 20
δ = 0
P = C ndash S + PV (X) + PV ( Dividend) or P = C + PV (X) ndash S + PV (δ)
647 = 280 + 100 (1+002)42365
- 9614 + 0
647 = 663 is not that valuable to go after the reprising arbitrage
PUT OPTION VALUATION
P = X e ndashiT
(1- N (d2)) ndash S e -δT
(1 - N (d1))
Using the data from previous example
P = 95 e ndash 10x25
(1 ndash 005714) ndash 100 (1 ndash 06664)
P = 635
PUT-CALL Parity
P = C + PV (X) ndash So + PV (Div)
P = 1370 + 95 e -10 X 025
ndash 100 + 0
Hedge Ratios amp the BS format
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
11
The Hedge ratio is commonly called the Option Delta Is the change in the price
of call option for $1 increased in the stock price
This is the slope of value function evaluated at the current stock price
For Example
Slope of the curve at S = $120 equals 60 As the stock increases by $1 the option
increase on 060
For every Call Option Written 60 shares of stock would be needed to hedge the
Investment portfolio
For example if one writes 10 options and holds 6 shares of stock
H = 60 helliphelliphellip a $1 increase in stock will result $6 gain ($1x 6 shares) and with
the loss of $6 on 10 options written (10 x $060)
The Hedge Ratio for a Call is N (d1)
with the hedge ratio for a Put [N (d1) ndash 1]
N (d) is the area under standard deviation (normal)
Therefore the Call option Hedge Ratio must be positive and less than 10
And the Put option Hedge Ratio is negative and less than 10
Example 165
2 Portfolios
Portfolio A B
BUY 750 IBM Calls
200 Shares of IBM
800 shares of IBM
Which portfolio has a greater dollar exposure to IBM price movement
Using the Hedge ratio you could answer that question
Each Option change in value by H dollars for each $1 change in stock price
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
12
If H = 06 then 750 options = equivalent 450 shares (06 x 750)
Portfolio A = 450 equivalent + 200 shares which is less than Portfolio B with 800
shares
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
6
d1 = [ln (10095) + (10-0 + 522)25] [ 5 SQRT of 25] = 43
d2 = 43 - 5 SQRT of 25 = 18
Next find N (d1) and d N(d2) The normal distribution function is tabulated and may be
found in many statistics books A table of N (d) is provided as Table 162 in the book
page 521 The normal distribution function N(d) is also provided in any spreadsheet
program In Excel the function name is NORMSDIST so using EXCEL (using
interpolation for 43) we find that
N(43) = 6664
N(18) = 5714
Finally remember that with dividends (δ) = o
S0 e ndash δT
= S0
Thus the value of the call option is
C = 100 x 6664 ndash 95e -10x025
x 5714
=6664 ndash 5294 = $1370
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
7
BLACK-SCHOLES OPTION VALUATION METHOD BS - CALL OPTION
A B C D E F G Compound at e
5
6 INPUT OUTPUT Face Value 100$
7 Interest 10
8 Standard Deviation (σ) = 05 d1 = 0430 Years 109 Expiration (in years) (T) = 025 d2 = 0180
10 Risk-Free Rate (Annual) (i) = 01 N(d1) = 0666 Description Compound FV
11 Stock Price (S ) = 100 N(d2) = 0571 Annual 1 25937425 12 Exercise Price (X) = 95 Semi 2 26532977
13 Dividend Yield (annual) (δ) = 0 C = 136953 Quarterly 4 26850638 Monthly 12 27070415
Daily 365 27179096
LONG CALCULATION (Break Down Approach) Hourly 8760 27182663
D1 = Ln ( S X ) ( i-δ+σ^2 2 ) σradict By Minute 525600 27182816 D1 = 0051293294 005625 025 By Second 31536000 27182819
Infinite e 27182818
D1 = 043017
N (d1) = 066647
PV calculation using e
D2= 018017 e = PV x (1+i)^t
N (d2) = 057149 PV = e (1+i)^t
PV = e ^-itC = 1370
2 BLACK-SCHOLES OPTION VALUATION METHOD BS - PUT OPTION
A B C D E F G Compound at e
32
33 INPUT OUTPUT Face Value 100$
34 Interest 10
35 Standard Deviation (σ) = 05 d1 = 0430 Years 10
36 Expiration (in years) (T) = 025 d2 = 0180
37 Risk-Free Rate (Annual) (i) = 01 N(d1) = 0666 Description Compound FV
38 Stock Price (S ) = 100 N(d2) = 0571 Annual 1 25937425
39 Exercise Price (X) = 95 Semi 2 26532977
40 Dividend Yield (annual) (δ) = 0 P = 63497 Quarterly 4 26850638
Monthly 12 27070415
Daily 365 27179096
LONG CALCULATION (Break Down Approach) Hourly 8760 27182663
D1 = Ln ( S X ) ( i-δ+σ^2 2 ) σradict By Minute 525600 27182816
D1 = 0051293294 005625 025 By Second 31536000 27182819
Infinite e 27182818
D1 = 0430173178
N (d1) = 0666465164
PV calculation using e
D2= 0180173178 e = PV x (1+i)^t
N (d2) = 0571491692 PV = e (1+i)^t
PV = e ^-itP = 63497
3 PUT-CALL PARITY METHOD FOR CALCULATING THE PUT OPTION KNOWING THE CALL PRICE (same data as above)
C - P = S - X e -it
P = Xe -it - S + C
P = 63497
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
8
Review ndash Options
C = S e -δT
N (d1) ndash X e ndashiT
N (d2)
P = X e ndashiT
(1- N (d2)) ndash S e -δT
(1 - N (d1))
Volatility is the question on the BS ndashwhich assumes constant SD throughout the exercise
period - The time series of implied volatility
THE PUT ndash CALL PARITY RELATIONSHIP
Put prices can be derived simply from the prices of call
European Put or Call options are linked together in an equation known as the Put-
Call parity relationship
St lt= X St gt X
Payoff of Call Held 0 St - X
Payoff of Put Written -(X ndash St) 0
Total St ndash X St ndash X
PV (x) = X e ndashrt
The option has a payoff identical to that of the leveraged equity position the costs of
establishing them must be equal
C ndash P Cost of Call purchased = Premium received from Put written
The leverage Equity position requires a net cash outlay of S ndash X e ndashrt
the Cost
of the stock less the process from borrowing
C ndash P = S ndash X e ndashrt
PUT-CALL Parity Relationship - proper relationship
between Call and Put
Example 163
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
9
S = $110
C = $14 for 6 months with X = $105
P = $5 for 6 months with X=$105
rf = 50 (continuously compounding at e )
Assumptions
C ndash P = S ndash X e ndashrT
14 ndash 5 = 110 ndash 105 e ndash 05 x 05
9 = 759
This a violation of parityhellip Indicates mispricing and leads to Arbitrage
Opportunity
You can buy relatively cheap portfolio (buy the stock plus borrowing position
represented on the right side of the equation and sell the expensive portfolio
STRATEGY ndash In six months the stock will be worth Sr so you borrow PV of X
($105) and pay back the loan with interest resulting in cash outflow of $105
Sr ndash 105 writing the call if Sr exceeds 105
Purchase Puts will pay 105 ndash Sr if the stock is below the $105
Strategy Immediate
CF
CF if
Sr lt 105
CF if
Sr gt 105
1 Buy Stock -11000 Sr Sr
2 Borrow Xe ndashiT
= $10241 +10241 -105 -105
3 Sell Call 1400 0 -(Sr ndash 105)
4 Buy Call -500 105 ndash Sr 0
141 0 0
Whish is the difference of between 900 and 759 ndash riskless return
This applies if No dividends and under the European option
If Dividend then
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
10
P = C ndash S + PV (X) + PV ( Dividend) hellip Representing that the Dividend (δ) is
paid during the life of the option
Example
Using the IBM example ndash today is February 6
X = $100 (March calls)
T = 42 days
C = $280
P = $647
S = 9614
I = 20
δ = 0
P = C ndash S + PV (X) + PV ( Dividend) or P = C + PV (X) ndash S + PV (δ)
647 = 280 + 100 (1+002)42365
- 9614 + 0
647 = 663 is not that valuable to go after the reprising arbitrage
PUT OPTION VALUATION
P = X e ndashiT
(1- N (d2)) ndash S e -δT
(1 - N (d1))
Using the data from previous example
P = 95 e ndash 10x25
(1 ndash 005714) ndash 100 (1 ndash 06664)
P = 635
PUT-CALL Parity
P = C + PV (X) ndash So + PV (Div)
P = 1370 + 95 e -10 X 025
ndash 100 + 0
Hedge Ratios amp the BS format
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
11
The Hedge ratio is commonly called the Option Delta Is the change in the price
of call option for $1 increased in the stock price
This is the slope of value function evaluated at the current stock price
For Example
Slope of the curve at S = $120 equals 60 As the stock increases by $1 the option
increase on 060
For every Call Option Written 60 shares of stock would be needed to hedge the
Investment portfolio
For example if one writes 10 options and holds 6 shares of stock
H = 60 helliphelliphellip a $1 increase in stock will result $6 gain ($1x 6 shares) and with
the loss of $6 on 10 options written (10 x $060)
The Hedge Ratio for a Call is N (d1)
with the hedge ratio for a Put [N (d1) ndash 1]
N (d) is the area under standard deviation (normal)
Therefore the Call option Hedge Ratio must be positive and less than 10
And the Put option Hedge Ratio is negative and less than 10
Example 165
2 Portfolios
Portfolio A B
BUY 750 IBM Calls
200 Shares of IBM
800 shares of IBM
Which portfolio has a greater dollar exposure to IBM price movement
Using the Hedge ratio you could answer that question
Each Option change in value by H dollars for each $1 change in stock price
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
12
If H = 06 then 750 options = equivalent 450 shares (06 x 750)
Portfolio A = 450 equivalent + 200 shares which is less than Portfolio B with 800
shares
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
7
BLACK-SCHOLES OPTION VALUATION METHOD BS - CALL OPTION
A B C D E F G Compound at e
5
6 INPUT OUTPUT Face Value 100$
7 Interest 10
8 Standard Deviation (σ) = 05 d1 = 0430 Years 109 Expiration (in years) (T) = 025 d2 = 0180
10 Risk-Free Rate (Annual) (i) = 01 N(d1) = 0666 Description Compound FV
11 Stock Price (S ) = 100 N(d2) = 0571 Annual 1 25937425 12 Exercise Price (X) = 95 Semi 2 26532977
13 Dividend Yield (annual) (δ) = 0 C = 136953 Quarterly 4 26850638 Monthly 12 27070415
Daily 365 27179096
LONG CALCULATION (Break Down Approach) Hourly 8760 27182663
D1 = Ln ( S X ) ( i-δ+σ^2 2 ) σradict By Minute 525600 27182816 D1 = 0051293294 005625 025 By Second 31536000 27182819
Infinite e 27182818
D1 = 043017
N (d1) = 066647
PV calculation using e
D2= 018017 e = PV x (1+i)^t
N (d2) = 057149 PV = e (1+i)^t
PV = e ^-itC = 1370
2 BLACK-SCHOLES OPTION VALUATION METHOD BS - PUT OPTION
A B C D E F G Compound at e
32
33 INPUT OUTPUT Face Value 100$
34 Interest 10
35 Standard Deviation (σ) = 05 d1 = 0430 Years 10
36 Expiration (in years) (T) = 025 d2 = 0180
37 Risk-Free Rate (Annual) (i) = 01 N(d1) = 0666 Description Compound FV
38 Stock Price (S ) = 100 N(d2) = 0571 Annual 1 25937425
39 Exercise Price (X) = 95 Semi 2 26532977
40 Dividend Yield (annual) (δ) = 0 P = 63497 Quarterly 4 26850638
Monthly 12 27070415
Daily 365 27179096
LONG CALCULATION (Break Down Approach) Hourly 8760 27182663
D1 = Ln ( S X ) ( i-δ+σ^2 2 ) σradict By Minute 525600 27182816
D1 = 0051293294 005625 025 By Second 31536000 27182819
Infinite e 27182818
D1 = 0430173178
N (d1) = 0666465164
PV calculation using e
D2= 0180173178 e = PV x (1+i)^t
N (d2) = 0571491692 PV = e (1+i)^t
PV = e ^-itP = 63497
3 PUT-CALL PARITY METHOD FOR CALCULATING THE PUT OPTION KNOWING THE CALL PRICE (same data as above)
C - P = S - X e -it
P = Xe -it - S + C
P = 63497
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
8
Review ndash Options
C = S e -δT
N (d1) ndash X e ndashiT
N (d2)
P = X e ndashiT
(1- N (d2)) ndash S e -δT
(1 - N (d1))
Volatility is the question on the BS ndashwhich assumes constant SD throughout the exercise
period - The time series of implied volatility
THE PUT ndash CALL PARITY RELATIONSHIP
Put prices can be derived simply from the prices of call
European Put or Call options are linked together in an equation known as the Put-
Call parity relationship
St lt= X St gt X
Payoff of Call Held 0 St - X
Payoff of Put Written -(X ndash St) 0
Total St ndash X St ndash X
PV (x) = X e ndashrt
The option has a payoff identical to that of the leveraged equity position the costs of
establishing them must be equal
C ndash P Cost of Call purchased = Premium received from Put written
The leverage Equity position requires a net cash outlay of S ndash X e ndashrt
the Cost
of the stock less the process from borrowing
C ndash P = S ndash X e ndashrt
PUT-CALL Parity Relationship - proper relationship
between Call and Put
Example 163
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
9
S = $110
C = $14 for 6 months with X = $105
P = $5 for 6 months with X=$105
rf = 50 (continuously compounding at e )
Assumptions
C ndash P = S ndash X e ndashrT
14 ndash 5 = 110 ndash 105 e ndash 05 x 05
9 = 759
This a violation of parityhellip Indicates mispricing and leads to Arbitrage
Opportunity
You can buy relatively cheap portfolio (buy the stock plus borrowing position
represented on the right side of the equation and sell the expensive portfolio
STRATEGY ndash In six months the stock will be worth Sr so you borrow PV of X
($105) and pay back the loan with interest resulting in cash outflow of $105
Sr ndash 105 writing the call if Sr exceeds 105
Purchase Puts will pay 105 ndash Sr if the stock is below the $105
Strategy Immediate
CF
CF if
Sr lt 105
CF if
Sr gt 105
1 Buy Stock -11000 Sr Sr
2 Borrow Xe ndashiT
= $10241 +10241 -105 -105
3 Sell Call 1400 0 -(Sr ndash 105)
4 Buy Call -500 105 ndash Sr 0
141 0 0
Whish is the difference of between 900 and 759 ndash riskless return
This applies if No dividends and under the European option
If Dividend then
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
10
P = C ndash S + PV (X) + PV ( Dividend) hellip Representing that the Dividend (δ) is
paid during the life of the option
Example
Using the IBM example ndash today is February 6
X = $100 (March calls)
T = 42 days
C = $280
P = $647
S = 9614
I = 20
δ = 0
P = C ndash S + PV (X) + PV ( Dividend) or P = C + PV (X) ndash S + PV (δ)
647 = 280 + 100 (1+002)42365
- 9614 + 0
647 = 663 is not that valuable to go after the reprising arbitrage
PUT OPTION VALUATION
P = X e ndashiT
(1- N (d2)) ndash S e -δT
(1 - N (d1))
Using the data from previous example
P = 95 e ndash 10x25
(1 ndash 005714) ndash 100 (1 ndash 06664)
P = 635
PUT-CALL Parity
P = C + PV (X) ndash So + PV (Div)
P = 1370 + 95 e -10 X 025
ndash 100 + 0
Hedge Ratios amp the BS format
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
11
The Hedge ratio is commonly called the Option Delta Is the change in the price
of call option for $1 increased in the stock price
This is the slope of value function evaluated at the current stock price
For Example
Slope of the curve at S = $120 equals 60 As the stock increases by $1 the option
increase on 060
For every Call Option Written 60 shares of stock would be needed to hedge the
Investment portfolio
For example if one writes 10 options and holds 6 shares of stock
H = 60 helliphelliphellip a $1 increase in stock will result $6 gain ($1x 6 shares) and with
the loss of $6 on 10 options written (10 x $060)
The Hedge Ratio for a Call is N (d1)
with the hedge ratio for a Put [N (d1) ndash 1]
N (d) is the area under standard deviation (normal)
Therefore the Call option Hedge Ratio must be positive and less than 10
And the Put option Hedge Ratio is negative and less than 10
Example 165
2 Portfolios
Portfolio A B
BUY 750 IBM Calls
200 Shares of IBM
800 shares of IBM
Which portfolio has a greater dollar exposure to IBM price movement
Using the Hedge ratio you could answer that question
Each Option change in value by H dollars for each $1 change in stock price
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
12
If H = 06 then 750 options = equivalent 450 shares (06 x 750)
Portfolio A = 450 equivalent + 200 shares which is less than Portfolio B with 800
shares
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
8
Review ndash Options
C = S e -δT
N (d1) ndash X e ndashiT
N (d2)
P = X e ndashiT
(1- N (d2)) ndash S e -δT
(1 - N (d1))
Volatility is the question on the BS ndashwhich assumes constant SD throughout the exercise
period - The time series of implied volatility
THE PUT ndash CALL PARITY RELATIONSHIP
Put prices can be derived simply from the prices of call
European Put or Call options are linked together in an equation known as the Put-
Call parity relationship
St lt= X St gt X
Payoff of Call Held 0 St - X
Payoff of Put Written -(X ndash St) 0
Total St ndash X St ndash X
PV (x) = X e ndashrt
The option has a payoff identical to that of the leveraged equity position the costs of
establishing them must be equal
C ndash P Cost of Call purchased = Premium received from Put written
The leverage Equity position requires a net cash outlay of S ndash X e ndashrt
the Cost
of the stock less the process from borrowing
C ndash P = S ndash X e ndashrt
PUT-CALL Parity Relationship - proper relationship
between Call and Put
Example 163
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
9
S = $110
C = $14 for 6 months with X = $105
P = $5 for 6 months with X=$105
rf = 50 (continuously compounding at e )
Assumptions
C ndash P = S ndash X e ndashrT
14 ndash 5 = 110 ndash 105 e ndash 05 x 05
9 = 759
This a violation of parityhellip Indicates mispricing and leads to Arbitrage
Opportunity
You can buy relatively cheap portfolio (buy the stock plus borrowing position
represented on the right side of the equation and sell the expensive portfolio
STRATEGY ndash In six months the stock will be worth Sr so you borrow PV of X
($105) and pay back the loan with interest resulting in cash outflow of $105
Sr ndash 105 writing the call if Sr exceeds 105
Purchase Puts will pay 105 ndash Sr if the stock is below the $105
Strategy Immediate
CF
CF if
Sr lt 105
CF if
Sr gt 105
1 Buy Stock -11000 Sr Sr
2 Borrow Xe ndashiT
= $10241 +10241 -105 -105
3 Sell Call 1400 0 -(Sr ndash 105)
4 Buy Call -500 105 ndash Sr 0
141 0 0
Whish is the difference of between 900 and 759 ndash riskless return
This applies if No dividends and under the European option
If Dividend then
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
10
P = C ndash S + PV (X) + PV ( Dividend) hellip Representing that the Dividend (δ) is
paid during the life of the option
Example
Using the IBM example ndash today is February 6
X = $100 (March calls)
T = 42 days
C = $280
P = $647
S = 9614
I = 20
δ = 0
P = C ndash S + PV (X) + PV ( Dividend) or P = C + PV (X) ndash S + PV (δ)
647 = 280 + 100 (1+002)42365
- 9614 + 0
647 = 663 is not that valuable to go after the reprising arbitrage
PUT OPTION VALUATION
P = X e ndashiT
(1- N (d2)) ndash S e -δT
(1 - N (d1))
Using the data from previous example
P = 95 e ndash 10x25
(1 ndash 005714) ndash 100 (1 ndash 06664)
P = 635
PUT-CALL Parity
P = C + PV (X) ndash So + PV (Div)
P = 1370 + 95 e -10 X 025
ndash 100 + 0
Hedge Ratios amp the BS format
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
11
The Hedge ratio is commonly called the Option Delta Is the change in the price
of call option for $1 increased in the stock price
This is the slope of value function evaluated at the current stock price
For Example
Slope of the curve at S = $120 equals 60 As the stock increases by $1 the option
increase on 060
For every Call Option Written 60 shares of stock would be needed to hedge the
Investment portfolio
For example if one writes 10 options and holds 6 shares of stock
H = 60 helliphelliphellip a $1 increase in stock will result $6 gain ($1x 6 shares) and with
the loss of $6 on 10 options written (10 x $060)
The Hedge Ratio for a Call is N (d1)
with the hedge ratio for a Put [N (d1) ndash 1]
N (d) is the area under standard deviation (normal)
Therefore the Call option Hedge Ratio must be positive and less than 10
And the Put option Hedge Ratio is negative and less than 10
Example 165
2 Portfolios
Portfolio A B
BUY 750 IBM Calls
200 Shares of IBM
800 shares of IBM
Which portfolio has a greater dollar exposure to IBM price movement
Using the Hedge ratio you could answer that question
Each Option change in value by H dollars for each $1 change in stock price
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
12
If H = 06 then 750 options = equivalent 450 shares (06 x 750)
Portfolio A = 450 equivalent + 200 shares which is less than Portfolio B with 800
shares
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
9
S = $110
C = $14 for 6 months with X = $105
P = $5 for 6 months with X=$105
rf = 50 (continuously compounding at e )
Assumptions
C ndash P = S ndash X e ndashrT
14 ndash 5 = 110 ndash 105 e ndash 05 x 05
9 = 759
This a violation of parityhellip Indicates mispricing and leads to Arbitrage
Opportunity
You can buy relatively cheap portfolio (buy the stock plus borrowing position
represented on the right side of the equation and sell the expensive portfolio
STRATEGY ndash In six months the stock will be worth Sr so you borrow PV of X
($105) and pay back the loan with interest resulting in cash outflow of $105
Sr ndash 105 writing the call if Sr exceeds 105
Purchase Puts will pay 105 ndash Sr if the stock is below the $105
Strategy Immediate
CF
CF if
Sr lt 105
CF if
Sr gt 105
1 Buy Stock -11000 Sr Sr
2 Borrow Xe ndashiT
= $10241 +10241 -105 -105
3 Sell Call 1400 0 -(Sr ndash 105)
4 Buy Call -500 105 ndash Sr 0
141 0 0
Whish is the difference of between 900 and 759 ndash riskless return
This applies if No dividends and under the European option
If Dividend then
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
10
P = C ndash S + PV (X) + PV ( Dividend) hellip Representing that the Dividend (δ) is
paid during the life of the option
Example
Using the IBM example ndash today is February 6
X = $100 (March calls)
T = 42 days
C = $280
P = $647
S = 9614
I = 20
δ = 0
P = C ndash S + PV (X) + PV ( Dividend) or P = C + PV (X) ndash S + PV (δ)
647 = 280 + 100 (1+002)42365
- 9614 + 0
647 = 663 is not that valuable to go after the reprising arbitrage
PUT OPTION VALUATION
P = X e ndashiT
(1- N (d2)) ndash S e -δT
(1 - N (d1))
Using the data from previous example
P = 95 e ndash 10x25
(1 ndash 005714) ndash 100 (1 ndash 06664)
P = 635
PUT-CALL Parity
P = C + PV (X) ndash So + PV (Div)
P = 1370 + 95 e -10 X 025
ndash 100 + 0
Hedge Ratios amp the BS format
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
11
The Hedge ratio is commonly called the Option Delta Is the change in the price
of call option for $1 increased in the stock price
This is the slope of value function evaluated at the current stock price
For Example
Slope of the curve at S = $120 equals 60 As the stock increases by $1 the option
increase on 060
For every Call Option Written 60 shares of stock would be needed to hedge the
Investment portfolio
For example if one writes 10 options and holds 6 shares of stock
H = 60 helliphelliphellip a $1 increase in stock will result $6 gain ($1x 6 shares) and with
the loss of $6 on 10 options written (10 x $060)
The Hedge Ratio for a Call is N (d1)
with the hedge ratio for a Put [N (d1) ndash 1]
N (d) is the area under standard deviation (normal)
Therefore the Call option Hedge Ratio must be positive and less than 10
And the Put option Hedge Ratio is negative and less than 10
Example 165
2 Portfolios
Portfolio A B
BUY 750 IBM Calls
200 Shares of IBM
800 shares of IBM
Which portfolio has a greater dollar exposure to IBM price movement
Using the Hedge ratio you could answer that question
Each Option change in value by H dollars for each $1 change in stock price
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
12
If H = 06 then 750 options = equivalent 450 shares (06 x 750)
Portfolio A = 450 equivalent + 200 shares which is less than Portfolio B with 800
shares
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
10
P = C ndash S + PV (X) + PV ( Dividend) hellip Representing that the Dividend (δ) is
paid during the life of the option
Example
Using the IBM example ndash today is February 6
X = $100 (March calls)
T = 42 days
C = $280
P = $647
S = 9614
I = 20
δ = 0
P = C ndash S + PV (X) + PV ( Dividend) or P = C + PV (X) ndash S + PV (δ)
647 = 280 + 100 (1+002)42365
- 9614 + 0
647 = 663 is not that valuable to go after the reprising arbitrage
PUT OPTION VALUATION
P = X e ndashiT
(1- N (d2)) ndash S e -δT
(1 - N (d1))
Using the data from previous example
P = 95 e ndash 10x25
(1 ndash 005714) ndash 100 (1 ndash 06664)
P = 635
PUT-CALL Parity
P = C + PV (X) ndash So + PV (Div)
P = 1370 + 95 e -10 X 025
ndash 100 + 0
Hedge Ratios amp the BS format
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
11
The Hedge ratio is commonly called the Option Delta Is the change in the price
of call option for $1 increased in the stock price
This is the slope of value function evaluated at the current stock price
For Example
Slope of the curve at S = $120 equals 60 As the stock increases by $1 the option
increase on 060
For every Call Option Written 60 shares of stock would be needed to hedge the
Investment portfolio
For example if one writes 10 options and holds 6 shares of stock
H = 60 helliphelliphellip a $1 increase in stock will result $6 gain ($1x 6 shares) and with
the loss of $6 on 10 options written (10 x $060)
The Hedge Ratio for a Call is N (d1)
with the hedge ratio for a Put [N (d1) ndash 1]
N (d) is the area under standard deviation (normal)
Therefore the Call option Hedge Ratio must be positive and less than 10
And the Put option Hedge Ratio is negative and less than 10
Example 165
2 Portfolios
Portfolio A B
BUY 750 IBM Calls
200 Shares of IBM
800 shares of IBM
Which portfolio has a greater dollar exposure to IBM price movement
Using the Hedge ratio you could answer that question
Each Option change in value by H dollars for each $1 change in stock price
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
12
If H = 06 then 750 options = equivalent 450 shares (06 x 750)
Portfolio A = 450 equivalent + 200 shares which is less than Portfolio B with 800
shares
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
11
The Hedge ratio is commonly called the Option Delta Is the change in the price
of call option for $1 increased in the stock price
This is the slope of value function evaluated at the current stock price
For Example
Slope of the curve at S = $120 equals 60 As the stock increases by $1 the option
increase on 060
For every Call Option Written 60 shares of stock would be needed to hedge the
Investment portfolio
For example if one writes 10 options and holds 6 shares of stock
H = 60 helliphelliphellip a $1 increase in stock will result $6 gain ($1x 6 shares) and with
the loss of $6 on 10 options written (10 x $060)
The Hedge Ratio for a Call is N (d1)
with the hedge ratio for a Put [N (d1) ndash 1]
N (d) is the area under standard deviation (normal)
Therefore the Call option Hedge Ratio must be positive and less than 10
And the Put option Hedge Ratio is negative and less than 10
Example 165
2 Portfolios
Portfolio A B
BUY 750 IBM Calls
200 Shares of IBM
800 shares of IBM
Which portfolio has a greater dollar exposure to IBM price movement
Using the Hedge ratio you could answer that question
Each Option change in value by H dollars for each $1 change in stock price
BARUCH COLLEGE ndash DEPARTMENT OF ECONOMICS amp FINANCE ndash FIN4710
Professor Chris Droussiotis
12
If H = 06 then 750 options = equivalent 450 shares (06 x 750)
Portfolio A = 450 equivalent + 200 shares which is less than Portfolio B with 800
shares